Blob Blame Raw
From 89a1609edd48f08e4227baa2890b96a936cfadb8 Mon Sep 17 00:00:00 2001
From: "Owen W. Taylor" <otaylor@fishsoup.net>
Date: Tue, 18 Aug 2015 15:19:05 -0400
Subject: [PATCH 32/47] logind: get a fresh file descriptor to clean up a VT

When the controlling process exits, any existing file descriptors
for that FD will be marked as hung-up and ioctls on them will
file with EIO. To work around this, open a new file descriptor
for the VT we want to clean up.

Thanks to Ray Strode for help in sorting out the problem and
coming up with a fix!

https://github.com/systemd/systemd/issues/989
---
 src/login/logind-session.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/login/logind-session.c b/src/login/logind-session.c
index a8e667b..9abdf62 100644
--- a/src/login/logind-session.c
+++ b/src/login/logind-session.c
@@ -1039,7 +1039,18 @@ void session_restore_vt(Session *s) {
         int vt, kb = K_XLATE;
         struct vt_mode mode = { 0 };
 
+        /* We need to get a fresh handle to the virtual terminal,
+         * since the old file-descriptor is potentially in a hung-up
+         * state after the controlling process exited; we do a
+         * little dance to avoid having the terminal be available
+         * for reuse before we've cleaned it up.
+         */
+        int old_fd = s->vtfd;
+        s->vtfd = -1;
+
         vt = session_open_vt(s);
+        safe_close(old_fd);
+
         if (vt < 0)
                 return;
 
-- 
2.5.0